3 of 3 Although I thought the original answer directly answered the question, I am underlining the point for those who missed it before.

At several siyums for my Daf Yomi group, I heard Rabbi Gedaliah Anemer tell a story involving Rav Moshe Feinstein, which he used to address the subject question.

Rabbi Anemer related that one of the Rav's students came from a non-yeshivish background. One day his father asked him to explain to him what it was they were learning in yeshiva. So, the son sat down to learn a page of Gemara with his father. When they completed an entire daf, the father told his son that he wanted to have a siyum. The son said "you can't have a siyum for just a single daf; you have a siyum for learning an entire mesechta of Gemara, but not a daf". The father told his son to ask Rav Moshe whether it could be done and, to the son's surprise, the Rav said that not only could it be done, he wanted to be invited. Soon thereafter the father died and Rav Moshe came to the funeral and told the story of the siyum, stating that by learning even a single daf of Gemara, the father had not only merited a siyum, he had earned a place in the World to Come.

When Rabbi Anemer told this story at siyums for the local daf yomi, he acknowledged that these men who work long days often fell asleep during the shiur, but nevertheless, they had earned a place in the World to Come because of their efforts to learn. Also, knowing that fact (that some of us lost consciousness during numerous sugyas), Rabbi Anemer still celebrated the siyumim with us all.